Any aircraft capable of refuelling a trimotor in flight, could easily take on its task. Ergo, that was not really well thought out - unless you wanted to offload 10 Victors into the bloody thing. More naivety.
I thought the purpose of the TriStar receiver capability was principally for Falklands emergency reinforcement as follows:
Formation of 4x FJs, 1x TriStar and 1x VC10 launch from ASI. VC10 refuels FJs (twice?) and then dumps rest of its remaining offload into the TriStar before turning back. TriStar then has enough fuel to get the the rest of the formation to MPA.
To update the scenario, 2 x FSTAs will have 20T more fuel available than 1 TriStar plus one VC10, and a considerably lower burn.